<!DOCTYPE html>
<html>

<head>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        html,
        body {
            background-color: #f3f3f3;
            height: 100%;
        }
        /*flex 布局 */
        .container {
            display: flex;
            flex-direction: column;
            width: 100%;
            height: 100%;
        }

        .content {
            width: 100%;
            height: 600px;
            background: red;
            flex: 1 0 auto;
        }

        .footer {
            height: 200px;
            width: 100%;
            background: yellow;
            flex: 0 0 auto;
        }
    </style>
</head>

<body>
    <div class="container">
        <div class="content">1321</div>
        <div class="footer">eadsd</div>
    </div>
</body>

</html>